This disclosure relates to bushings constrained by compression in levered apparatus, and more particularly to elastomeric torsion bushings which provide pivots for lever arms used to drive motion of acoustic diaphragms in loudspeakers.
U.S. patent application Ser. No. 14/200,614, filed Mar. 7, 2014 describes a levered loudspeaker that employs elastomeric torsion bushings to provide pivots for lever arms to drive motion of an acoustic diaphragm. The bushings are bonded, e.g., via adhesive or molded-in-place, at their outer and inner diameters.
Elastomers are almost incompressible, and typically shrink at curing, leading to high residual stresses at bushing ends. This is especially true for highly confined configurations, i.e., when the bushing length is much larger than the difference of its outer and inner diameters.